Cell cycle controls are organized into a loop, so that cycles may occur over and over again. These controls are of several kinds: transcriptional controls, proteolytic controls, protein kinase controls, etc. The development of microarray technology has now made it far easier and more efficient to investigate all kinds of transcriptional controls. Indeed, microarray studies on the transcriptional regulation of the cell cycle have provided a wealth of data. In this proposal, microarray technology will be used to continue the study of the transcriptional control of the yeast cell cycle. In particular, an overview of the circular nature of cell cycle controls will be sought. In Aim 1, we will complete the task of assigning cell cycle regulated genes to their regulating transcription factors. In Aim 2, we will find out how the time at which cell cycle genes are expressed is determined, and we will define the extent and mechanisms of combinatorial control in the cycle. In Aim 3, we will test the hypothesis that an oscillation in the state of histone acetylation is a major mechanism of cell cycle transcriptional control. [unreadable] [unreadable]